A movable mirror of such a type that the movable mirror is displaced according to an electrostatic attractive force is expected to be applied in various fields that use light. For example, the movable mirror can be used as a wavefront correction device for adaptive optics which is incorporated in a fundus examination apparatus, an astronomical telescope, and the like. A typical example of the method which employs such a movable mirror that is displaced according to an electrostatic attractive force includes a method of displacing the movable mirror using two parallel flat electrodes. However, a small displacement amount is one of the drawbacks of the parallel flat electrodes.
In contrast, a movable mirror which provides a larger displacement amount using comb electrodes has been proposed recently. An example thereof is disclosed in PTL 1. As shown in FIG. 14, in this movable mirror, a supporting portion 530 that supports an comb electrode 520 on the moving side and a supporting portion 570 that supports an comb electrode 510 on the stationary side are respectively located above and below in the vertical direction on the drawing sheet. The movable comb electrode and the stationary comb electrode face each other and are disposed alternately. Due to this, since an overlapped area is larger than that of the conventional example that uses parallel flat electrodes, the electrostatic attractive force increases, and the displacement amount can be increased.